Vikram and I are waffling on this question, so I thought I'd throw it out for everybody's feedback:
For signed error estimates, e.g. estimates of Quantity-of-Interest error where Q - Q_h ~= sum_E ( \eta_E ), what should the estimate_error() method put in our ErrorVector? The signed eta_E, or the unsigned abs(eta_E)? On the one hand: if error vectors can contain signed values, then every MeshRefinement heuristic is going to have to be modified to do abs() calls itself, 99% of the time this is going to be a complete waste, and (given that the ErrorEstimator subclass also calculates a global "Q - Q_h" estimate that can be accessed without that summation) it's hard to come up with usage cases for the signed local values. On the other hand: since abs() doesn't require any more cache misses or use any more memory bandwidth, doing it redundantly in MeshRefinement local variables may not actually waste time on modern processors. And if someone ever *does* want to use signed local values for something (cancellation-aware refinement heuristics??) then it would be good if we didn't destroy that sign information before giving local values to them. Opinions, or factors I've missed? --- Roy ------------------------------------------------------------------------------ Don't let slow site performance ruin your business. Deploy New Relic APM Deploy New Relic app performance management and know exactly what is happening inside your Ruby, Python, PHP, Java, and .NET app Try New Relic at no cost today and get our sweet Data Nerd shirt too! http://p.sf.net/sfu/newrelic-dev2dev _______________________________________________ Libmesh-devel mailing list Libmesh-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-devel
